Switched power converters are widely used to convert between DC (direct current) source and load as well as to interface to slowly moving AC (alternating current) inputs and outputs. These uses represent one mode of operation of switched power converters. For the purpose of improving efficiency of RF (radio frequency) power amplifiers, a variable supply is used to power the amplifier. The switched power converter providing the variable supply must have a high efficiency, very low switching noise, high bandwidth and slew rate. This represents a different mode of operation for a switched power converter. Using conventional control schemes which have been developed for essentially DC sources and loads, these objectives can be met only by switching at a rate much higher than the envelope bandwidth, resulting in lower efficiency and EMI (electromagnetic interference) problems. A new method and device are needed specifically for providing an efficient linear power amplifier that generates a variable envelope radio frequency RF signal that alleviates such problems.